Abstract:

A mold for a battery, such as a secondary battery, and a method of molding
a battery, such as a secondary battery, using the mold, uses a minimum
amount of a molding substance, such as a resin, has its molding time
shortened, and has a safety vent of a can being prevented from being
fractured by high pressure during a molding process. Runners, through
which a resin flows, are arranged parallel to cavities and the safety
vent of the can is positioned closest to the gates, into which a resin is
injected after the can and a protective circuit board are seated in the
cavities. Due to the structure of the runners of the mold and the
location of the safety vent of the can, the amount of resin used and the
molding time are reduced. A fracture of the safety vent is avoided since
a lower pressure occurs at the location closest to the gates during a
resin filling process.

Claims:

1. A mold comprising:a lower mold including a first runner arranged on an
upper surface thereof, the first runner having a predetermined depth and
extending linearly a predetermined length, the first runner arranged to
have a resin injected therein and to pass therethrough;at least one first
gate having a predetermined depth and connected to the first runner, the
at least one first gate arranged to guide the resin along a direction,
the first gate having a first cavity formed on a side of the first runner
and having a predetermined depth, the cavity arranged to accommodate a
can and a protective circuit board therein, the can and the protective
circuit board arranged to have a predetermined gap defined therebetween
while being electrically connected to each other; andan upper mold having
a second runner, a second gate, and a second cavity arranged on a lower
surface thereof, the second runner having the same shape and arranged at
a location corresponding to that of the first runner, the second gate
having the same shape and arranged at a location corresponding to that of
the first gate, and the second cavity having the same shape and arranged
at a location corresponding to that of the first cavity.

2. The mold as recited in claim 1, wherein the first and second cavities
are each of a rectangular shape having short and long sides, and wherein
the first and second gates are arranged to be in communication with the
gap with an angle of between 10.degree. to 80.degree. at a location of
the long side of their respective cavity corresponding to the gap.

3. The mold as recited in claim 2, wherein the first and second runners
are arranged parallel to the long side of their respective cavity.

4. The mold as recited in claim 1, wherein the first and second gates have
slant surfaces arranged such that the closer to the gap between the can
and the protective circuit board, the smaller the cross-sectional area
through which the resin passes after passing through the first and second
gates becomes.

5-12. (canceled)

13. A mold comprising:a lower mold including a first runner arranged on an
upper surface thereof, the first runner having a predetermined depth and
extending linearly a predetermined length, the first runner arranged to
have a molding substance injected therein and to pass therethrough;at
least one first gate having a predetermined depth and connected to the
first runner, the at least one first gate arranged to guide the molding
substance along a direction, the first gate having a first cavity formed
on a side of the first runner and having a predetermined depth, the
cavity arranged to accommodate a can and a board therein, the can and the
board arranged to have a predetermined gap defined therebetween while
being electrically connected to each other; andan upper mold having a
second runner, a second gate, and a second cavity arranged on a lower
surface thereof, the second runner having the same shape and arranged at
a location corresponding to that of the first runner, the second gate
having the same shape and arranged at a location corresponding to that of
the first gate, and the second cavity having the same shape and arranged
at a location corresponding to that of the first cavity.

14. The mold as recited in claim 13, wherein the first and second cavities
are each of a rectangular shape having short and long sides, and wherein
the first and second gates are arranged to be in communication with the
gap with an angle of between 10.degree. to 80.degree. at a location of
the long side of their respective cavity corresponding to the gap.

15. The mold as recited in claim 14, wherein the first and second runners
are arranged parallel to the long side of their respective cavity.

16. The mold as recited in claim 13, wherein the first and second gates
have slant surfaces arranged such that the closer to the gap between the
can and the protective circuit board, the smaller the cross-sectional
area through which the molding substance passes after passing through the
first and second gates becomes.

17-20. (canceled)

Description:

CLAIM OF PRIORITY

[0001]This application makes reference to, incorporates the same herein,
and claims all benefits accruing under 35 U.S.C. §119 from
applications for MOLD FOR SECONDARY BATTERY and METHOD FOR MOLDING
SECONDARY BATTERY earlier filed in the Korean Intellectual Property
Office on 15 Mar. 2004 and 30 Mar. 2004 and there duly assigned Serial
No. 2004-17436 and 2004-21423.

BACKGROUND OF THE INVENTION

[0002]1. Field of the Invention

[0003]The present invention relates to molding a battery, and more
particularly, the present invention relates to a mold for a battery and a
method of molding a battery, such as a secondary battery, using the mold,
wherein a minimum amount of a molding substance, such as a resin, is used
to retain a board, such as a protective circuit board, on the battery,
resulting in the molding time using the resin being shortened and a
safety vent of a battery can being prevented from being fractured by high
pressure during a molding process.

[0004]2. Description of the Prior Art

[0005]As generally known in the art, a secondary battery, particularly a
square-type lithium ion secondary battery electrically connects a
protective circuit board to the positive and negative terminals of a can
(battery sheath), in order to protect the battery from overcharging,
over-discharging, an over-current, a short due to an external load, and
the like. The can has a safety vent, which has a smaller wall thickness
than that of the remainder of the can, formed on a side of the negative
terminal so that if abnormal pressure occurs, the safety vent is
fractured and internal gas is discharged to the exterior.

[0006]Both the can and the protective circuit board are contained in a
sheath cover, which is composed of an upper cover and a lower cover, and
are shipped as a product, in order to enhance the mechanical coupling
strength between the can and the protective circuit board and protect
them from external environments.

[0007]Recently, a method has been used wherein the gap between the can and
the protective circuit board is filled with a resin or wherein the can
and the protective circuit board are completely coated with a resin, in
order to reduce the number of parts and improve the productivity. For
example, upper and lower molds are provided with cavities, in which cans
and protective circuit boards are to be contained, and gates and runners,
which are connected to the cavities and act as channels for the resin
during filling. Both the cans and the protective circuit boards are then
seated on the cavities of the upper and lower molds and a resin, which
has high temperature and high pressure, is injected toward the cavities
through the runners and the gates, which are in communication with the
runners. As a result, the cans and protective circuit boards are firmly
mechanically retained by the resin.

[0008]However, such molds have a problem in that the runners, which act as
channels for the resin, are formed a great distance away from the
cavities and the amount of resin, which remains in the runners and the
gates, is larger than that which is used to fill the gap between the cans
and the protective circuit boards. This wastes the resin. In particular,
after the resin molding is completed and the batteries are removed from
the molds, the resin, which remains in the runners and the gates of the
molds, is in a hardened state. Consequently, the expensive resin, which
cannot be reused, must be removed from the runners and gates and disposed
of.

[0009]In addition, it takes a long time for the resin to reach the
cavities, because the runners are positioned away from the cavities and
are very long. This prolongs the filling time. It is also likely that the
cavities, in particular, the gap between the cans and the protective
circuit boards, are not completely filled with the resin and the process
ends in that state. This results in a poor molding of the secondary
battery.

[0010]Conventional resin molding methods also have a problem in that,
since the safety vent of the can is positioned farther from the gate into
which the resin is injected, the safety vent is vulnerable to fracture
due to the resin filling pressure. This is because the farther from the
gate into which the resin flows, the higher the air pressure due to the
resin filling becomes, and the safety vent, which has a smaller wall
thickness than that of the remainder of the can, can be fractured toward
the interior of the can by such high pressure.

[0011]If the safety vent is fractured in this way, a secondary problem can
occur, i.e., the resin at a high pressure can penetrate into the can, and
the electrolyte can easily leak to the exterior along the interface
between the can and the resin during use of the battery.

SUMMARY OF THE INVENTION

[0012]Accordingly, the present invention has been made to solve the
above-mentioned problems occurring in the prior art, and an object of the
present invention is to provide a mold for a battery, such as a secondary
battery, that minimizes the waste of a molding substance, such as a
resin, used to retain a board, such as a protective circuit board, in a
battery can.

[0013]Another object of the present invention is to provide a mold for a
battery that minimizes the molding time using a resin.

[0014]Still another object of the present invention is to provide a method
of molding a battery that prevents the fracture of a safety vent of a can
due to high pressure during a process of molding a can and a protective
circuit board in a mold using a resin.

[0015]In order to accomplish these and other objects, a mold is provided
comprising: a lower mold including a first runner arranged on an upper
surface thereof, the first runner having a predetermined depth and
extending linearly a predetermined length, the first runner arranged to
have a resin injected therein and to pass therethrough; at least one
first gate having a predetermined depth and connected to the first
runner, the at least one first gate arranged to guide the resin along a
direction, the first gate having a first cavity formed on a side of the
first runner and having a predetermined depth, the cavity arranged to
accommodate a can and a protective circuit board therein, the can and the
protective circuit board arranged to have a predetermined gap defined
therebetween while being electrically connected to each other; and an
upper mold having a second runner, a second gate, and a second cavity
arranged on a lower surface thereof, the second runner having the same
shape and arranged at a location corresponding to that of the first
runner, the second gate having the same shape and arranged at a location
corresponding to that of the first gate, and the second cavity having the
same shape and arranged at a location corresponding to that of the first
cavity.

[0016]The first and second cavities are preferably each of a rectangular
shape having short and long sides, and wherein the first and second gates
are arranged to be in communication with the gap with an angle of between
10° to 80° at a location of the long side of their
respective cavity corresponding to the gap.

[0017]The first and second runners are preferably arranged parallel to the
long side of their respective cavity.

[0018]The first and second gates preferably have slant surfaces arranged
such that the closer to the gap between the can and the protective
circuit board, the smaller the cross-sectional area through which the
resin passes after passing through the first and second gates becomes.

[0019]In order to further accomplish these and other objects, a method is
provided comprising: arranging a can to have a positive terminal on a
front surface thereof, a negative terminal next to a side of the positive
terminal, and a safety vent next to a side of the negative terminal;
electrically connecting the positive and negative terminals of the can to
a protective circuit board; arranging a mold to have a cavity of a
predetermined depth, the cavity being arranged to integrally seat the can
and the protective circuit board thereon to have a gate next to a side of
the cavity to guide a flow of resin through a gap between the can and the
protective circuit board and to have a runner to be in communication with
the gate to guide the flow of resin; seating the can and the protective
circuit board on the cavity of the mold to position the gate of the mold
at a lateral portion of the gap between the can and the protective
circuit board; and injecting a resin into the runner such that the resin
passes through the gate and is injected into the gap between the can and
the protective circuit board seated inside the cavity.

[0020]The method preferably further comprises positioning the safety vent
of the can between the negative terminal and the gate.

[0021]The method preferably further comprises arranging a distance between
the safety vent of the can and the gate to be smaller than a distance
between the negative terminal and the gate.

[0022]The method preferably further comprises positioning the safety vent
of the can adjacent to the gate.

[0023]The method preferably further comprising injecting the resin to pass
through the safety vent of the can, the negative and positive terminals
successively, the resin adhering to the safety vent of the can, the
negative and positive terminals and filling the gap.

[0024]A resin injection trace preferably remains on a portion of the resin
adjacent to the gate after injecting the resin.

[0025]A resin injection trace preferably remains on the lateral portion of
the resin adjacent to the safety vent after injecting the resin.

[0026]The method preferably further comprises interposing an insulating
sheet between the safety vent of the can and the protective circuit
board.

[0027]In order to yet further accomplish these and other objects, a mold
is provided comprising: a lower mold including a first runner arranged on
an upper surface thereof, the first runner having a predetermined depth
and extending linearly a predetermined length, the first runner arranged
to have a molding substance injected therein and to pass therethrough; at
least one first gate having a predetermined depth and connected to the
first runner, the at least one first gate arranged to guide the molding
substance along a direction, the first gate having a first cavity formed
on a side of the first runner and having a predetermined depth, the
cavity arranged to accommodate a can and a board therein, the can and the
board arranged to have a predetermined gap defined therebetween while
being electrically connected to each other; and an upper mold having a
second runner, a second gate, and a second cavity arranged on a lower
surface thereof, the second runner having the same shape and arranged at
a location corresponding to that of the first runner, the second gate
having the same shape and arranged at a location corresponding to that of
the first gate, and the second cavity having the same shape and arranged
at a location corresponding to that of the first cavity.

[0028]The first and second cavities are preferably each of a rectangular
shape having short and long sides, and wherein the first and second gates
are arranged to be in communication with the gap with an angle of between
10° to 80° at a location of the long side of their
respective cavity corresponding to the gap.

[0029]The first and second runners are preferably arranged parallel to the
long side of their respective cavity.

[0030]The first and second gates preferably have slant surfaces arranged
such that the closer to the gap between the can and the protective
circuit board, the smaller the cross-sectional area through which the
molding substance passes after passing through the first and second gates
becomes.

[0031]In order to yet further accomplish these and other objects, a method
is provided comprising: arranging a can to have a first terminal on a
front surface thereof, a second terminal next to a side of the first
terminal, and a safety vent next to a side of the second terminal;
electrically connecting the first and second terminals of the can to a
board; arranging a mold to have a cavity of a predetermined depth, the
cavity being arranged to integrally seat the can and the board thereon;
arranging a gate next to a side of the cavity to guide a flow of a
molding substance through a gap between the can and the board and
arranging a runner to be in communication with the gate to guide the flow
of a molding substance; seating the can and the board on the cavity of
the mold to position the gate of the mold at a lateral portion of the gap
between the can and the board; and injecting a molding substance into the
runner such that the molding substance passes through the gate and is
injected into the gap between the can and the board seated inside the
cavity.

[0032]The method preferably further comprises positioning the safety vent
of the can between the second terminal and the gate.

[0033]The method preferably further comprises arranging a distance between
the safety vent of the can and the gate to be smaller than a distance
between the second terminal and the gate.

[0034]The method preferably further comprises positioning the safety vent
of the can adjacent to the gate.

[0035]The method preferably further comprises injecting the molding
substance to pass through the safety vent of the can, the second and
first terminals successively, the molding substance adhering to the
safety vent of the can, the second and first terminals, and filling the
gap.

[0036]A molding substance injection trace preferably remains on a portion
of the molding substance adjacent to the gate after injecting the molding
substance.

[0037]A molding substance injection trace preferably remains on the
lateral portion of the molding substance adjacent to the safety vent
after injecting the molding substance.

[0038]The method preferably further comprises interposing an insulating
paper between the safety vent of the can and the board.

[0039]According to the mold for a battery of the present invention, as
mentioned above, the runners, through which the resin is injected and
passes, are formed parallel to the direction of the long sides of the
cavities so that the resin travels the shortest path and the waste of the
resin is minimized.

[0040]It is also possible to minimize the molding time using the resin,
because the resin travels along the lateral portions of the cavities and
then fills the gap between the can and the protective circuit board.

[0041]According to the method of molding a battery of the present
invention, the safety vent of the can is not fractured by high pressure
during a molding process, because the safety vent is positioned closest
to the gate, the pressure of which is lower during the molding process.

[0042]Consequently, the safety vent can still work normally even after the
completion of resin molding. This prevents the resin from being injected
to the interior through the safety vent of the can or any electrolyte
from leaking to the exterior.

BRIEF DESCRIPTION OF THE DRAWINGS

[0043]A more complete appreciation of the present invention, and many of
the attendant advantages thereof, will be readily apparent as the present
invention becomes better understood by reference to the following
detailed description when considered in conjunction with the accompanying
drawings in which like reference symbols indicate the same or similar
components, wherein:

[0044]FIG. 1A is an exploded perspective view of a mold for a secondary
battery according to an embodiment of the present invention;

[0045]FIG. 1B is a perspective view of a can and a protective circuit
board seated on the mold of FIG. 1;

[0046]FIG. 2A is an exploded perspective view of a can and a protective
circuit board which are to be molded by a mold for a secondary battery
according to an embodiment of the present invention;

[0047]FIG. 2B is a perspective view of the rear side of a protective
circuit board;

[0048]FIG. 3A is a perspective view of seating a can and a protective
circuit board on a mold during a method of molding a secondary battery
according to an embodiment of the present invention;

[0049]FIG. 3B is a top view of a can and a protective circuit board seated
on a lower mold with an upper mold omitted;

[0052]FIG. 4A is a top view of the gap between a can and a protective
circuit board being filled with a resin during a method of molding a
secondary battery according to an embodiment of the present invention;

[0053]FIG. 4B is a sectional view taken along line 3-3 of FIG. 4A; and

[0054]FIG. 5 is a perspective view of a secondary battery which has been
molded according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0055]Hereinafter, exemplary embodiments of the present invention will be
described with reference to the accompanying drawings. In the following
description and drawings, the same reference numerals are used to
designate the same or similar components, and a repetition of the
description of the same or similar components has been omitted.

[0056]FIG. 1A is an exploded perspective view of a mold for a secondary
battery according to an embodiment of the present invention and referring
to FIG. 1B is a view of the can and the protective circuit board seated
on the mold of FIG. 1A.

[0057]A mold for a secondary battery according to an embodiment of the
present invention includes a lower mold 100, on which a can 10 and a
protective circuit board 17 are seated with a gap 27 defined between
them, and an upper mold 200, which is fastened on top of the lower mold
100 so that a resin can be injected to fill the gap 27.

[0058]The lower mold 100 has a first runner 110 formed on its upper
surface 101, which extends linearly a predetermined length and which has
a predetermined depth, so that a resin can be injected and flow through
it. At least one first gate 120 is formed to be in communication with the
first runner 110 and to guide the resin along a direction which is angled
relative to that of the runner 110. A first cavity 130 is formed next to
a side of the first runner 110, which has a predetermined depth and is in
communication with the first gate 120 so that a can 10 and a protective
circuit board 17 can be seated thereon with a predetermined gap 27
defined between them while they are electrically connected to each other.

[0059]The first cavity 130 can be of a substantially rectangular shape
having short and long sides 131 and 132. The first gate 120 is in
communication with the long side 132 with an angle of 10° to
80° at a location corresponding to that of the gap 27. In other
words, the first gate 120 is in communication with the gap 27 between the
can 10 and the protective circuit board 27. Accordingly, a resin can be
directly injected into the gap 27 after passing through the first gate
120. Of course, the first cavity 130 can also be of a regular square
shape, instead of a rectangular shape, and the shape of the first cavity
130 is not limited in the present invention.

[0060]The first runner 110 can be formed parallel to the long side 132 of
the first cavity 130 for minimized length. This arrangement makes it
possible to minimize the amount of resin remaining in the first runner
110 and the first gate 120 after completion of molding, and to shorten
the time for injecting a resin. Even when the first cavity 130 is of a
substantially regular square shape, the first runner 110 can, of course,
still be formed parallel to a side thereof.

[0061]The upper mold 200 has the same shape as the lower mold 100. In
particular, the upper mold 200 has a second runner 210 formed on its
lower surface 201, which is fastened on the upper surface 101 of the
lower mold 100, in the same shape at a location corresponding to that of
the first runner 110. The upper mold 200 also has a second gate 220
formed in the same shape at a location corresponding to that of the first
gate 120 and a second cavity 230 formed in the same shape at a location
corresponding to that of the first cavity 130. The second cavity 230 can,
of course, be of a rectangular shape having short and long sides 231 and
232.

[0062]The resin flows into the gap 27 between the cap 10 and the
protective circuit board 17 along a direction as marked by a solid arrow
in the drawing.

[0063]According to another aspect of the present invention, a method of
molding a secondary battery includes: electrically connecting a can and a
protective circuit board to each other; providing a mold; seating the can
and the protective circuit board on the mold, and filling the mold with a
resin.

[0064]Electrically connecting a can and a protective circuit board to each
other is described below with reference to FIGS. 2A and 2B.

[0065]A front surface of the can 10 is provided with a safety vent 11, a
negative terminal 13 surrounded by an insulator 12, and a positive
terminal 14. The negative terminal 13 is coupled to a negative lead 15
and the positive terminal 14 is coupled to a positive lead 16. The can 10
has a substantially rectangular-shaped protective circuit board 17
positioned in front of the can 10 to protect the battery from
overcharging, over-discharging, an over-current, a short due to external
load, and the like. A front surface of the protective circuit board 17 is
provided with a type determination terminal 19, an external negative
terminal 20, and an external positive terminal 21. The protective circuit
board 17 also has a number of round protrusions 22a and 22b formed on the
upper and lower portions thereof, which protrude to the exterior and are
to be interlocked with a resin later. An insulating paper 26 can be
additionally interposed between the protective circuit board 17 and the
can 10 to prevent the negative lead 15 from contacting the positive
region of the can 10 and the safety vent 11 fractured by high pressure
during resin filling.

[0066]A rear surface of the protective circuit board 17 is provided with a
protective circuit portion 23, a negative connection terminal 24 to which
the negative lead 15 is connected, and a positive connection terminal 25
to which the positive lead 16 is connected.

[0067]Seating the can and the protective circuit board on the mold is
described below with reference to FIGS. 3A to 3E.

[0068]FIG. 3A is a perspective view of the can and the protective circuit
board seated on the mold. FIG. 3B is a top view of the can and the
protective circuit board seated on a lower mold without an upper mold.
FIG. 3C is a top view magnifying area 1 of FIG. 3B and FIG. 3D is a
sectional view taken along line 2-2 of FIG. 3B.

[0069]The can 10 and the protective circuit board 17 are seated between
the first cavity 130, which is formed on the upper surface 101 of the
lower mold 100, and the second cavity 230, which is formed on the lower
surface 201 of the upper mold 200.

[0070]The gap 27 between the can 10 and the protective circuit board 17 is
positioned in such a manner that it faces the first and second gates 120
and 220. In particular, the safety vent 11, which is formed on the can 10
with a smaller wall thickness than that of the remainder of the can 10,
is positioned closest to the first and second gates 120 and 220.
Specifically, the safety vent 11 is positioned between the negative
terminal 13 and the first and second gates 120 and 220. In other words,
the distance between the safety vent 11 and the first and second gates
120 and 220 is smaller than that between the negative terminal 13 and the
first and second gates 120 and 220. More particularly, the safety vent 11
of the can 10, the negative lead 15, and the positive lead 16 are
positioned successively from the first and second gates 120 and 220. The
safety vent 11 is positioned at the right ends of the first and second
cavities 130 and 230, which are closest to the first and second gates 120
and 220, the negative lead 15 is positioned near the center of the first
and second cavities 130 and 230, and the positive lead 16 is positioned
at the left ends of the first and second cavities 130 and 230, as shown
in FIG. 3C. Of course, the location of the gap 27 between the can 10 and
the protective circuit board 17 can be identical to that of the first and
second gates 120 and 220, as mentioned above. As a result, the gap 27 can
easily be filled with the resin, which has passed through the first and
second runners 110 and 210 and the first and second gates 120 and 220.
The first and second gates 120 and 220 can have slant surfaces 121 and
221 of a smaller width so that the closer to the gap 27 between the can
10 and the protective circuit board 17, the smaller the cross-sectional
area, through which the resin passes after passing through the first and
second gates 120 and 220, becomes.

[0071]FIG. 4A is a view of the gap 27 between the can 10 and the
protective circuit board 17 being filled with a resin during the method
for molding a secondary battery according to an embodiment of the present
invention and FIG. 4B is a sectional view taken along line 3-3 of FIG.
4A.

[0072]After the can 10 and the protective circuit board 17 are seated, a
resin 18 of high temperature and high pressure (temperature: about
200-300 degrees, pressure: about 0.5-1.0 MPa) is injected through the
first and second runners 110 and 120. The injected resin 18 then passes
through the first and second gates 120 and 220, which are formed in the
shape of a tree together with the first and second runners 110 and 210,
and is moved toward the first and second cavities 130 and 230 for
filling. In particular, the resin 18 fills the gap 27 between the can 10
and the protective circuit board 17. As mentioned above, the resin 18
adheres successively to the safety vent 11 of the can 10, the negative
and positive leads 15 and 16. Finally, the resin 18 completely retains
the can 10 and the protective circuit board 17 in a mechanical fashion.

[0073]The air pressure established in the gap 27 has the smallest value at
a point of time when the resin 18 has passed through the first and second
gates 120 and 220. This is because the air remaining in the gap 27 has
not yet been compressed very much by the resin 18. In such a low-pressure
state, the resin 18 goes past the safety vent 11, particularly the
insulating paper 26 fastened on the surface thereof, and the safety vent
11 is not subject to high pressure.

[0074]After going past the safety vent 11 and the negative lead 15, the
resin 18 approaches the positive lead 26 and greatly compresses the air.
This increases the air pressure drastically. However, the can 10 is not
easily fractured by such a high pressure, because the can 10, which is
connected to the positive lead 26 and the positive terminal 14, has no
thin wall region located at the high pressure area.

[0075]As shown in FIG. 4B, a round protrusion 22a formed on the lower
portion of the protective circuit board 17 is forced against the bottom
surface of the cavity 130 of the lower mold 100 and a round protrusion
22b formed on the upper portion is forced against the bottom surface of
the cavity 230 of the upper mold 200. As a result, a predetermined gap
27a is formed between the protective circuit board 17 and the first
cavity 130 of the lower mold 100 and a predetermined gap 27b is formed
between the protective circuit board 17 and the second cavity 230 of the
upper mold 200 by the round protrusions 22a and 22b. Of course, a type
determination terminal 19, an external negative terminal 20, and an
external positive terminal 21, which are formed on the protective circuit
board 17, are forced against the lateral wall of the first cavity 130 of
the lower mold 10 and against that of the second cavity 230 of the upper
mold 200. Accordingly, when the gap 27 between the can 10 and the
protective circuit board 17 is filled with a resin during a resin filling
process, the space 27', which is defined at the front to surface of the
protective circuit board 17 by the gaps 27a and 27b, is also filled with
the resin simultaneously. Of course, the resin cannot reach the surfaces
of the terminals 19, 20, and 21, because they are forced against the
lateral surfaces of the first and second cavities 130 and 230.

[0076]FIG. 5 is a perspective view of a secondary battery which has been
molded according to a method of molding a secondary battery according to
an embodiment of the present invention.

[0077]A resin 18 completely retains a protective circuit board (not shown)
on a can 10 in a mechanical fashion. Of course, the above-mentioned type
determination terminal 19, external negative terminal 20, and external
positive terminal 21 are exposed from the front surface of the resin 18
for type determination and easy charging and discharging. A round
protrusion (not shown) of the protective circuit board 17 is also
completely surrounded by the resin 18, so that the protective circuit
board 17 is retained on the can 10 in a more stable manner.

[0078]After the removal of the secondary battery, any resin 18 remaining
in the first runner 110 and the first gate 120 in a hardened state is
removed and another resin filling process is performed successively for
another can and protective circuit board.

[0079]Reference numeral 18' refers to a remaining trace of the resin 18
which has passed through the first and second gates 120 and 220. In
particular, physical separation occurs between the resin 18 and a resin
remnant, which remains in the first and second gates 120 and 220, when
the secondary battery is removed from the mold after the completion of
the molding process, and the trace 18' of the separation is left. Of
course, a safety vent 11 is formed on the can 10, which is closest to the
trace 18'.

[0080]As mentioned above, the mold for a secondary battery according to
the present invention is advantageous in that the runners, through which
a resin is injected and passes, are formed parallel to the direction of
the long sides of cavities so that the resin travels the shortest path
and the waste of the resin is minimized.

[0081]It is also possible to minimize the molding time using the resin,
because the resin travels along the lateral portions of the cavities and
then fills the gap between the can and the protective circuit board.

[0082]According to the method for molding a secondary battery of the
present invention, the safety vent of the can is not fractured by high
pressure during a molding process, because the safety vent is positioned
closest to the gate, the pressure of which is lower during the molding
process.

[0083]Consequently, the safety vent can still work normally even after the
completion of resin molding. This prevents the resin from being injected
to the interior through the safety vent of the can or any electrolyte
from leaking to the exterior.

[0084]Although exemplary embodiments of the present invention have been
described for illustrative purposes, those skilled in the art will
appreciate that various modifications, additions and substitutions are
possible, without departing from the scope and spirit of the present
invention as recited in the accompanying claims.